By Lori E. Apodaca, C. Michelle Smith, and Jeffrey B. Bails

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In cooperation with Grand County

The Fraser River watershed is located in the southeastern part of Grand County, Colorado. The Fraser River flows about 28 river miles from its headwaters along the Continental Divide in the Arapaho National Forest through the towns of Winter Park, Fraser, Tabernash, and Granby and into the Colorado River (fig. 1). Grand County covers 1,869 square miles; the Fraser River watershed comprises about 16 percent of the county (about 302 square miles).The annual precipitation in the watershed ranges from 20 inches per year north and west of Fraser to more than 40 inches per year in the higher peaks near the Continental Divide. Land use/land cover in the watershed is 71 percent forested land; 14 percent agriculture and rangeland; 11 percent tundra, bare ground, or exposed rock; 2 percent urban; and 2 percent other land-use classifications (fig. 1; Fegeas and others, 1983).

The population of Grand County (estimated 1997 population of 9,879) has increased 138 percent between 1970 and 1997 (U.S. Bureau of the Census, 1970, 1997). In the upper part of the watershed upgradient from Tabernash, there are three wastewater-treatment facilities and public water supplies that serve the larger urban centers. Homes located outside the urban centers rely on well water and individual septic disposal systems (ISDS’s). With the increase in population, local agencies are concerned about a high density of ISDS’s and their potential effects on the future water quality in the watershed. In addition, the increased use (withdrawal) of ground water in the study area also is a factor that may affect the water quality. The U.S. Geological Survey (USGS), in cooperation with Grand County, began a 5-year study in 1998 to evaluate the ground-water quality in the Fraser River watershed. Twenty wells (18 domestic, 1 municipal, and 1 monitoring) were randomly selected in the watershed upgradient from Tabernash to determine baseline ground-water-quality conditions in this part of the watershed. The majority of the sites were randomly selected by using a stratified random selection computer program (Scott, 1990). The results from this study and the continued monitoring of 10 wells are intended to aid land-use planners in preserving water quality of the Fraser River watershed for Grand County residents and visitors.

TABLE OF CONTENTS

Introduction
Data Collection
Quality Assurance/Quality Control
Geologic and Hydrologic Characteristics
Ground-Water Quality
Ground-Water Age and Source
Summary and Conclusions
References Cited